The invention may be employed for the graphic representation and analysis of fluorescence signals, especially for the decay behavior of such signals, which can be used, for example, to investigate the bonding of dyes to substances in biological cells.
Equipment is known for the fluorescence analysis of microobjects, for which the whole of the object constantly encounters the beam of exciting radiation. With this equipment, an image of the object structure, which normally is viewed with eyepieces or which also can be investigated photometrically, is outlined by means of the fluorescence radiation emanating from the object. These solutions of the problem have the disadvantage that the fluorescence intensity decreases during the investigation and that consecutively measured values are not directly comparable. The possibility of a short-time analysis of the fluorescence process exists (Beyer, H., Hanbush de Mikroskopie (Handbook of Microscopy), Berlin, 1977). a short-time analysis is necessary when the objects to be investigated emit fluorescing radiation, which cannot be separated adequately by wavelength-dispersive means from the fluorescing radiation of the surroundings, as described in the German Patent No. 2,818,841.
Equipment is furthermore known for the short-time fluorescence analysis of the smallest object sites, for which an extremely short light pulse is focussed through a microobjective onto the sample and the variation with time of the fluorescence pulse emanating from the irradiated object site is recorded by means of fast photoelectric receivers and subsequently shown graphically and/or analyzed mathematically, as described by Docchio, F., et al., in Journ. Microsc. 134 (1984) 151. This equipment is free of so-called fading and offers the possibility of timeresolved fluorometry. In principle, it is admittedly possible with this equipment to obtain through repeated application an overview of the spatial distribution of substances with a timewise different fluorescence response, but only if much time is expended on the procedure.
To eliminate this difficulty, the proposal is made in the German Patent No. 3,037,983 C2 to use a receiver diode array in the scanning direction in the focal plane of a scanning microscope. This ensures again only a slight time resolution and can be used only with relatively slowly decaying fluorescence and therefore not with most of the important natural fluorescences of biological cells or with other normal fluorochromes.
Admittedly, the solution to the problem described in the U.S. Pat. No. 4,284,897 largely limits fading; however, it contains no means for analyzing the fluorescence process as a function of time.